1. Field of the Invention
The present invention relates to a printer having a multi-color ribbon which has a plurality of ink colors arrayed substantially orthogonally to the ribbon winding direction, and to a control method for the printer. More specifically, the present invention relates to a printer in which winding of the ink ribbon is performed in conjunction with moving a carriage on which the print head is carried, and to a control method for the printer.
2. Description of the Related Art
Printers that use an ink ribbon cartridge continue to be widely used due to their high printing reliability and relatively low cost. When a cartridge is loaded into the printer, the ribbon that is pulled out from the cartridge is positioned in the gap between the print head and paper along the path of print head movement. A winding mechanism inside the cartridge gradually winds the ink ribbon in conjunction with movement of the carriage and print head, and thus maintains a fresh section of the ink ribbon disposed in the print head-paper gap.
The ribbon used in this type of printer has a plurality of colors of ink arrayed across the width of the ink ribbon, that is, in the direction orthogonal to the ink ribbon winding direction. Such a ribbon is referred to below as a multi-color ink ribbon. By changing the relative positions of the ink ribbon and the print head in this widthwise direction, it is possible to print in multiple colors. That is, when a command for printing in a specific color accompanies the print command, the printer controller moves the position of the ink ribbon relative to the print head, or the position of the print head relative to the ribbon, so as to bring the desired color on the ink ribbon in front of the print head. Then, the print head is driven to print.
Such printers have, however, suffered from one common problem. When changing the relative position of the ink ribbon to the print head, the ink ribbon can catch on the face or edge of the print head, resulting in the desired color area on the ink ribbon (referred to also below as the print track) not being correctly positioned in front of the print head. Thus, there is a misalignment between the ink ribbon and the print head. The result is that the desired color is not used for printing immediately after changing the color position of the ribbon, and the desired color gets mixed with another color.
An arm of the cartridge normally keeps a specific tension on the ink ribbon, and thus alleviates the problem of the ribbon getting caught. Over time, however, the arm tension tends to weaken, or the ink ribbon gets slightly twisted or off track in the direction of its width, and the above-noted problem occurs.
Proposed solutions for this problem include various methods of winding the ink ribbon a specific distance after changing the relative positions of the print head and ribbon so as to move the ink ribbon to the desired position, that is, properly align the ribbon with the print head.
For example, Japanese Unexamined Patent Application Publication (kokai) 6-87256 teaches a color mixing prevention device for a printer. This device winds a specific length of ribbon either while shifting the position of the ink ribbon or after the ink ribbon has been shifted to remove slack from the ribbon and move the ribbon to the correct position.
Japanese Unexamined Patent Application Publication (kokai) 8-207405 teaches a printer for positively removing ink ribbon slack by changing the amount of ink ribbon that is wound according to the distance the ink ribbon is shifted to change its position.
Japanese Unexamined Patent Application Publication (kokai) 5-131736 teaches a printer designed to drive a ribbon winding mechanism using a carriage motor for bidirectionally moving the carriage. A ribbon shifting motor is driven to shift the ribbon position while the carriage motor is accelerating or decelerating as a way of preventing ink ribbon jams and enabling high-speed printing.
However, a problem common to the above-noted methods of the related art is that printing throughput declines after changing the print color (i.e., the position of the ink ribbon). More specifically, the following process is typically performed when a command specifying a color different from the previous color is sent to the printer.
(1) Change the relative positions of the print head and ink ribbon.
(2) Wind the ribbon a specific distance (this can be done simultaneously with step (1) above).
(3) Move the print head to the print start position.
(4) Print.
However, this process may be wasteful in a printer in which the ink ribbon is wound in conjunction with moving the carriage on which the print head is carried. For example, moving the print head to the print start position in step (3) may, as a result of carriage movement and depending upon the location of the next print position, sufficiently wind the ink ribbon to correct any offset or misalignment of the ribbon position. In this case the time spent performing step (2) above is unnecessary. In addition, excess ribbon is wound and thus wasted.
Therefore, it is an object of the present invention to overcome the aforementioned problems.
Considering the above disadvantages in the related art, it is an object of the present invention to provide a printer and a control method for the same whereby problems relating to an offset in the ink ribbon position when changing the ink ribbon color can be eliminated as much as possible without reducing printing throughput.
To achieve above objects, the present invention provides a printer having a print head that moves relative to a print medium; an ink ribbon disposed in front of the print head along the direction of print head movement such that the ink ribbon is wound in conjunction with print head movement. The ink ribbon has a plurality of ink colors arranged substantially orthogonally to the direction in which the ink ribbon is wound. A switching mechanism is provided for switching the position of the print head relative to the ink ribbon in a direction orthogonal to the ink ribbon winding direction. A controller moves the print head in a non-printing winding mode a distance Lxe2x88x92l after the relative position of the print head to ribbon is switched by the switching mechanism when distance l of print head movement in conjunction with ink ribbon winding to the next print start position is less than a specific distance L for correcting ink ribbon offset to the print head.
It should be noted that this non-printing winding mode as used herein involves moving the print head while winding the ink ribbon without driving the print head to print for the purpose of correcting misalignment of the ink ribbon with the print head.
When thus comprised the print head is moved in this non-printing winding mode only when moving the print head in conjunction with ink ribbon winding will not wind the ink ribbon the required distance to correct misalignment. As a result, a reduction in print throughput accompanying switching the ink ribbon position can be minimized.
The controller in this printer preferably determines the position of the print head after being moved in the non-printing winding mode based on the next print start position.
This makes it possible to minimize the time required to move the print head to the next print start position when non-printing winding mode movement of the print head is necessary.
Yet further preferably, the ink ribbon is wound in conjunction with print head movement in only one direction, and the switching mechanism switches when the print head is outside the printable area of the print head.
Another printer according to the present invention for achieving the above object is a printer for printing using an ink ribbon having a plurality of print tracks with the printer comprising: a print head for printing with the ink ribbon on a print medium; a moving mechanism for bidirectionally moving the print head in a direction across a print medium transportation direction; a winding mechanism for winding the ink ribbon in conjunction with print head movement; a shift mechanism for changing the position of the print track relative to the print head; and a controller for determining, after switching by said switching mechanism starts, whether a distance l is equal to a specific distance L, and moving the print head in a non-printing winding mode a distance Lxe2x88x92l to wind the ink ribbon when print head movement distance l is less than specific distance L. This print head movement distance l is the distance of print head movement to the next print start position accompanied by ink ribbon winding. This non-printing winding mode is as noted above.
This printer according to the present invention determines the distance and direction of print head in the non-printing winding mode based on the next print start position and the printing direction.
The present invention also achieves the above object by providing a printer control method. This control method applies to a printer comprising a print head that moves relative to a print medium; an ink ribbon disposed in front of the print head along a direction of movement of the print head, the ink ribbon being wound in conjunction with print head movement and having a plurality of ink colors arranged substantially orthogonally to this winding direction; and a switching mechanism for switching the position of the print head relative to the ink ribbon in a direction orthogonal to the ink ribbon winding direction. The control method comprises the following steps: changing the position of the print head relative to the ink ribbon by means of the switching mechanism; comparing a distance l and a specific distance L, and moving the print head at least a distance Lxe2x88x92l in a non-printing winding mode if distance l is less than specific distance L. Distance l as used herein is the distance of print head movement to the next print start position with the ink ribbon being wound as the print head moves, and specific distance L is the distance for correcting misalignment of the ink ribbon to the print head, typically as a result of shifting the relative position of the print head to the ribbon. The non-printing winding mode is as described above.
A further control method according to the present invention is a printer control method for a printer for printing using an ink ribbon having a plurality of print tracks. This control method comprises: printing on a print medium with the ink ribbon using a print head; moving the print head bidirectionally on a path crossing the direction in which the print medium is transported; winding the ink ribbon in conjunction with print head movement; changing the position of the print track relative to the print head; determining whether a distance l is equal to a specific distance L after or during changing the ribbon to print head alignment, and moving the print head in a non-printing winding mode a distance Lxe2x88x92l to wind the ink ribbon when print head movement distance l is less than specific distance L based on the result of the determining step. This distance l is also the distance of print head movement to the next print start position accompanied by ink ribbon winding, and the non-printing winding mode is as noted above.
This second method further preferably comprises a step for deciding the nonprinting winding mode distance and direction based on the next print start position and print direction.
The control method of the present invention can also be provided as a control program executable by a printer controller, and can be provided by a data storage medium on which the control program is recorded. Storage media and devices that can be used for this data storage medium of the invention include: memory, Compact Discs, particularly CD-ROM media; floppy disks; hard disks; magneto-optical disks; DVD media such as DVD-ROM discs; and magnetic tape. Furthermore, these media can be used to supply this control program to existing printers. Yet further, the program can be made available on a World Wide Web (WWW) site from which users can download the program for use with an existing printer.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.